1. Field
The present disclosure generally relates to systems and methods of generating power from wind and, in particular, using pyroelectric materials to generate power from turbulent airflow.
2. Description of the Related Art
Traditional approaches to wind generation focus on capturing energy from steady wind flow, requiring turbine blades with large capture areas mounted far above the ground. Horizontal-axis wind turbines offer an efficient means to harvest energy from steady air flow. Moving air turns propeller blades, which in turn drive the shaft of an electrical generator. While all aspects of these turbines, from propeller aerodynamics to power conversion electronics, have been optimized over more than a century of development, several key limitations remain. The central challenge is that the efficiency of horizontal-axis designs is predicated on steady wind flow. Turning the propellers into the wind is necessary to take advantage of their optimized aerodynamics, and this yaw cannot happen arbitrarily quickly without inducing severe torques. In addition to steady air flow, the wind speed must exceed the “cut-in” velocity of the turbine to overcome the significant inertia associated with long propellers. Most horizontal-axis wind turbines have cut-in velocities around 4 m/s (10 mph).
Steady, high-speed wind requires turbines, for optimal power generation, to be placed as high as possible and far away from obstructions such as trees and buildings. In the United States, existing commercial wind farms are located in remote areas, such as the mountains around Tehachapi, Calif. or the major off-shore farm planned for the waters near Cape Cod, Mass. Delivering substantial amounts of power from these locations to populated areas requires a robust electrical grid and entails transmission and distribution losses of approximately 10%. The desire to harvest energy from weaker, less-directional winds near urban areas has spurred the development of vertical-axis wind turbines, which rotate about a central axis and can be driven by wind from any direction. These turbines sacrifice some of the efficiency of horizontal-axis systems, but in addition to being omni-directional, their reduced cut-in speeds permit operations in weaker winds. While attempts have been made to adapt both horizontal- and vertical-axis wind turbines to urban use, such systems must still be installed on the roofs of tall buildings to achieve even moderate conversion efficiencies. Few locations in built-up areas have steady wind flow in any direction, limiting the utility of traditional turbine systems.